The present invention relates to a disc brake for a motor vehicle brake system, comprising a brake support which has at least one receiving region; a brake lining arrangement which has a brake lining support and a brake lining which is attached to the brake lining support and which can be brought into interaction with a brake disc in order to achieve a braking effect, wherein the brake lining arrangement is received in the at least one receiving region in a guided manner via a guiding portion formed on the brake lining support; and at least one restoring spring which engages the brake lining arrangement and biases the brake lining arrangement under elastic deformation into a starting position that does not produce a braking effect, wherein the at least one restoring spring can be plastically deformed in order to compensate for brake lining wear.
Such disc brakes are prior art. In these disc brakes the brake lining support, after a deflection from its starting position that produces a braking effect whereby it moves into frictional contact with a brake disc, has to be moved back into the starting position in order to separate the brake lining from the brake disc. In order to avoid unnecessary wear and reduce consumption, after the brake lining arrangement has been deflected so as to produce a braking effect it is absolutely necessary to prevent any contact from remaining between brake lining and brake disc and any residual sliding moments from arising.
However, as is likewise generally known, it is necessary to configure the disc brake in such a way that in the event of wear at the brake linings a wear correction may be effected so that, despite the occurrence of lining wear, the behaviour of the disc brake upon actuation remains substantially constant. Such wear correction entails adjusting the restoring spring in accordance with the wear. For this purpose there are solutions, whereby in the receiving region the restoring spring may effect a sliding adjustment in accordance with the actual wear situation. Other solutions provide that the restoring spring deforms, in particular plastically deforms, in the receiving region in accordance with the actual wear. Such a solution is described for example in the document U.S. Pat. No. 7,318,503 B2. Here, the brake lining arrangement is biased into its starting position by means of a loop-shaped restoring spring, wherein the loop-shaped restoring spring is configured so as also to guarantee a lining wear compensation by means of a plastic deformation component.
It has however been shown that such solutions do not exhibit reliable behaviour during wear compensation. In particular, it is difficult to predict whether a plastic deformation of the spring curve always corresponds precisely to the actual wear state. A consequence of this is that with progressive brake lining wear in practice the restoring behaviour of the restoring spring may also vary. This may lead to the spring being for example overly deformed, with the result that the remaining elastic deformation component no longer provides an adequate restoring movement and residual sliding moments occur. On the other hand it is equally possible for the spring to be insufficiently plastically deformed, with the result that it provides a greater restoring travel than is desired. This leads to a delayed response behaviour of the brake upon renewed actuation.